Pervaporation Process Research Articles

Interlayer-free hybrid carbon-silica membranes for processing brackish to brine salt solutions by pervaporation

Mesoporous, interlayer-free, hybrid carbon-silica matrices and membranes based on tetraethoxysilane (TEOS), organosilica of triethoxyvinylsilane (TEVS) and pluronic triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (P123) were successfully prepared using an acid-base catalysed sol-gel method for desalination applications. These membranes were carbonized to form the hybrid carbon-silica structures under inert conditions in vacuum and nitrogen. The effects of calcination conditions on the structure-property relationship of the carbon-silica xerogels were elucidated, and the membrane performances were systematically studied using brackish (1wt%) to brine (15wt%) feed concentrations of sodium chloride solution and feed temperatures (25–60°C) under pervaporation process. Vacuum calcined (CS-Vc) membrane produced a slightly more mesoporous matrix and higher carbon yield than the nitrogen calcined (CS-N2) membrane, and hence, led to comparatively superior desalination performance. CS-Vc membranes produced high water fluxes of 26.5 (1wt%, 60°C) and 9.2 (15wt%, 60°C) Lm−2h−1 with salt rejections of 99.5% and 98.6%, respectively. This study demonstrates that the combined strategy of hybrid organosilica with polymeric template and vacuum calcination offered the carbonized silica mesostructure membranes with excellent separation of water from the hydrated salt ions, and importantly, high water fluxes particularly for processing brine salt solutions.

Spray-assisted biomineralization of a superhydrophilic water uptake layer for enhanced pervaporation dehydration

The membrane surface wettability is one of the most important factors influencing the solution-diffusion-controlled pervaporation process. In this work, a novel conceptual methodology for the construction of a superhydrophilic water uptake layer is proposed to overcome the limitation of trade-off effects. Rapid implementation of this strategy is possible by spray-assisted biomineralization of calcium carbonate (CaCO3) onto a (poly(acrylic acid)/poly(ethyleneimine))n/polyacrylonitrile ((PAA/PEI)n/PAN) membrane. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of a hierarchical lotus CaCO3 layer with calcite crystals on the outermost layer. The water contact angle dramatically decreased from 74° to 4.2° after biomineralizing CaCO3 micro-nano-particles. In the pervaporation separation of ethanol/water mixtures, the water content could be enriched from 5wt% to 98.8wt% while the permeate flux reached 1317g/(m2h), which is almost five times that of a pure polyelectrolyte membrane without biomineralizing CaCO3. This suggests that the CaCO3 water uptake layer plays a very important role in achieving high flux. These results indicate that biomineralization of micro-nano-particles is a facile strategy to fabricate a superhydrophilic surface and, in turn, improve the membrane performance.

Preparation and characterization of poly(Ether block amide)/graphene membrane for recovery of isopropanol from aqueous solution via pervaporation

In the present research, for the first time, hydrophobic graphene nanoplatelets were used as filler to prepare novel poly(ether block amide) /graphene membranes for enhancing the removal of isopropanol from the aqueous solution by pervaporation (PV) process. Graphene at the concentrations of 0.5, 1, 1.5, and 2 wt% was added to the polymeric solutions. The membranes were characterized using tests of scanning electron microscopy, X‐ray diffractometer, thermogravimetric analysis, mechanical strength, degree of swelling, and contact angle. The pervaporation experiments were accomplished using the feed containing 4 wt% of isopropanol at 50°C and permeate pressure of 20 mm Hg. The results showed that with the addition of graphene, thermal stability, tensile strength, and hydrophobicity of the prepared membranes were increased. Permeate flux, separation factor, and swelling degree of the prepared membranes were increased with the initial increase in the graphene content, whereas when the graphene content exceeded 1–1.5 wt%, these parameters decreased. The highest separation factor (10.04) and isopropanol flux (248.5 g/(m2 h)) were obtained for the hybrid membrane containing 1.5 wt% graphene in the polymeric solution. POLYM. COMPOS., 39:2259–2267, 2018. © 2016 Society of Plastics Engineers

Promising bioethanol processes for developing a biorefinery in the Moroccan sugar industry

In order to establish a cost-effective biorefinery in Moroccan sugar plants, the use of sugarcane bagasse and beet pulp to produce bioethanol is considered as a promising option. In fact, lately this efficient way of biomass conversion into bioethanol, which is a cleaner source of energy, has received a lot of interest. In this context, the main objective of the present paper is to conduct a comparative study between the most investigated processes of producing bioethanol from lignocellulosic biomass. This study has considered the technical, economical, and environmental criteria to select the most efficient processes for a large scale production. For each step of the studied process, the most efficient options have been selected. In the pretreatment step, the use of dilute sulfuric acid was selected as the best option followed by steam explosion method. In the hydrolysis step, dilute sulfuric acid was also adopted. Concerning the following step, co-culture fermentation using a respiratory mutant of Saccharomyces cerevisiae and Pichia stipitis has been found to give the best result. In the last step, conventional distillation process coupled with pervaporation has been chosen as the best way to produce high purity anhydrous ethanol; while molecular sieves and extractive distillation in dividing-wall columns using ethylene glycol was also considered as promising alternatives of the pervaporation process.

Dehydration of Organic Solutions by a Recirculated Air Sweep Pervaporation Process Using Anion-Exchange Hollow Fibers

An air sweep pervaporation process with thin anion-exchange hollow fibers was investigated for various water-organic solvent mixtures at different operating conditions. It was found that flux and separation factor increased with a decrease of the dielectric constant of the organic solvent. When the temperature of the process was increased, the flux increased. At feed temperatures of 65–70°C it was possible to reduce the water concentration in a 3–10% isopropyl alcohol (IPA) solution to 0.5%. The energy requirement for decreasing the water concentration in IPA from 3–10% to 0.5% was 100–225 kWh ton-1.

Pervaporation membrane bioreactor with permeate fractional condensation and mechanical vapor compression for energy efficient ethanol production

Improved process separation factor and heat integration are two key issues to increase the energy efficiency of ethanol production in a pervaporation membrane bioreactor (PVMBR). A PVMBR with permeate fractional condensation and mechanical vapor compression was developed for energy efficient ethanol production. A condensation model based on the mass balance and thermodynamic equilibrium in the partial vacuum condenser was developed for predicting the purification performance of the permeate vapor. Three runs of ethanol fermentation-pervaporation experiment were carried out and ethanol concentration of higher than 50wt% could be achieved in the final condensate, with the separation factor of the process for ethanol increased to 20. Ethanol production could be enhanced in the bioreactor and 17.1MJ of the energy could be produced in per liter of fermentation broth, owing to 27.0MJ/kg heating value of the recovered ethanol. Compared with the traditional pervaporation process with low temperature condensation for ethanol production, 50% of the energy would be saved in the process. The energy consumption would be further reduced, if the available energy of the permeate vapor was utilized by integrating the mechanical vapor compression heat pump.

Layer by Layer Composite Membranes of Alginate-Chitosan Crosslinked by Glutaraldehyde in Pervaporation Dehydration of Ethanol

Hydrophilicity of membrane causing only water can pass through membrane. Pervaporation process using organophilic membrane has been offered as alternative for ethanol dehydration. This paper investigate pervaporation based biopolymer composite membrane from alginate-chitosan using layer by layer method prepared by glutaraldehyde as crosslinking agent and polyethersulfone (PES) as supported membrane. Characterization of crosslinked of composite membrane by FTIR helped in identification of sites for interaction between layers of membrane and support layer (PES). The SEM showed a multilayer structure and a distinct interface between the chitosan layer, the sodium alginate layer and the support layer. The coating sequence of membranes had an obvious influence on the pervaporation dehydration performance of membranes. For the dehydration of 95 wt% ethanol-water mixtures, a good performance of PES-chitosan-alginate-chitosan (PES/Chi/Alg/Chi) composite membrane was found in the pervaporation dehydration of ethanol. Article History: Received April 12nd , 2016; Received in revised form June 25th , 2016; Accepted July 1st , 2016; Available onlineHow to Cite This Article: Rokhati, N., Istirokhatun, T. and Samsudin, A.M. (2016) Layer by Layer Composite Membranes of Alginate-Chitosan Crosslinked by Glutaraldehyde in Pervaporation Dehydration of Ethanol. Int. Journal of Renewable Energy Development, 5(2), 101-106.http://dx.doi.org/10.14710/ijred.5.2.101-106

Process intensification in a photocatalytic membrane reactor: Analysis of the techniques to integrate reaction and separation

Different methods to integrate reaction and separation in a membrane reactor are studied in the present work, with the aim being to highlight the pros and cons of the different alternatives and the effects of the intervening parameters. The coupling of the two processes can take place inside a single apparatus or using separate units. If a single apparatus is utilized, the coupling is more direct, but separate units offer higher degrees of freedom for the design with more opportunities to optimize the system without constraints. However, when using separate units, the integration of the two unit operations depends largely on the parameters intervening in the coupling procedure. These parameters are the recycle ratio, R, if a recycle stream is used to backmix part of the exiting stream, or the number, N, of blocks if the volume of the reaction and the membrane area are fractionated into multiple reaction-separation blocks. The possibility of different combinations of these two basic methods is also presented.The case study to illustrate the effect of the various parameters (R, N, the Damköhler number and the Péclet number) and to find the proper operating conditions is the photocatalytic green synthesis of an aromatic aldehyde, which is recovered from the reaction solution by a pervaporation process to avoid further oxidation. The results show that process intensification is the result of appropriately choosing the reaction system and operating conditions because these factors may substantially increase the yield.

Pervaporation performance in PDMS membrane bioreactor for ethanol recovery with running water and air as coolants at room temperature

AbstractBACKGROUNDPervaporation performance in a PDMS membrane bioreactor for ethanol recovery from model solution and fermentation broth was researched. Downstream of the membrane the permeate vapor was completely condensed by running water and air at room temperature.RESULTSPart of the permeate vapor was condensed under vacuum conditions by running water at room temperature in condenser C1, with ethanol concentration of 47.2 g L−1 obtained. The vacuum pump in the pervaporation membrane bioreactor was used to compress and pump the non‐condensed permeate vapor with ethanol concentration of 461.3 g L−1 into the condenser C2, where the vapor could be easily condensed under atmospheric conditions by air at room temperature. During the experimental ethanol recovery from model solution the total flux and separation factor were about 1100 g m−2 h−1 and 8.0, respectively, while the permeate flux of the membrane was reduced during the separation of fermentation broth.CONCLUSIONCompared with a traditional pervaporation process, the cold trap condensation was eliminated in the process and enhanced ethanol fermentation was achieved since pervaporation was continuously coupled with fermentation. © 2016 Society of Chemical Industry

Towards Acid-Tolerated Ethanol Dehydration: Chitosan-Based Mixed Matrix Membranes Containing Cyano-Bridged Coordination Polymer Nanoparticles.

Prussian blue (PB) nanoparticles, one of many cyano-bridged coordination polymers, are successfully incorporated into chitosan (CS) polymer to prepare PB/CS mixed matrix membranes (MMMs). The PB nanoparticles are uniformly distributed in the MMMs without the collapse of the original PB structure. As-prepared PB/CS MMMs are used for ethanol dehydration at 25 °C in the pervaporation process. The effect of loading PB in CS matrix on pervaporation performance is carefully investigated. The PB/CS membrane with 30 wt% PB loading shows the best performance with a permeate flux of 614 g. m-2 . h-1 and a separation factor of 1472. The pervaporation using our PB/CS membranes exhibits outstanding performance in comparison with the previously reported CS-based membranes and MMMs. Furthermore, the addition of PB allows PB/CS MMMs to be tolerant of acidic environment. The present work demonstrates good pervaporation performance of PB/CS MMMs for the separation of an ethanol/water (90:10 in wt%) solution. Our new system provides an opportunity for dehydration of bioethanol in the future.

Mathematical model of mass transfer processes of pervaporation water purification

Object. Theoretical studies of pervaporation separation of water -organic mixture by mathematical modeling of process.Design. Methodology . Approach. The current state of the problem, namely the existing mathematical model of membrane processes had been analyzed. After analysis of features of pervaporation purification process the mathematical model was formulated. The mathematical model describes the pervaporation of organic liquid component through the non-porous membrane in a circular cross section channel. Initial and boundary conditions for this mathematical model had been recorded. Without these conditions the solution is impossible Conclusions. Solution of the equations of mathematical model with the initial and boundary conditions allows to determine the concentration distribution of liquid flow which passes the membrane, and also though the membrane thickness depending on the size of the membrane, the modes of motion of initial and gas-vapor mixture, the concentration of organic impurities in initial and gas-vapor mixture. A mathematical model allows to finding a mode of operating of unit at which completely realized possibilities of membranes and minimized the cost of liquid heating and condensate cooling. In further the research of experimental studies of pervaporation process are planned to continue, to confirm the results obtained by mathematical modeling.

Energy saving potential of hybrid membrane and distillation process in butanol purification: Experiments, modelling and simulation

Pervaporation experiments of dilute aqueous butanol solutions were carried out with three PDMS [poly(dimethyl siloxane)] membranes. Based on the experimental results of the best performing membrane a regression for both butanol and water permeability was done in the software R and implemented in a user defined pervaporation unit operation in the software Aspen Custom Modeler. With the implementation of the pervaporation step in Aspen Plus the hybrid pervaporation and distillation purification chain can be simulated in consistent way.Calculation of pervaporation of a 0.5wt% BuOH-water solution with the experimentally investigated PDMS membrane results in a permeate stream with a concentration of 9wt% BuOH. Application of membrane distillation resulted in a permeate butanol concentration of only 3wt% and a considerable higher specific energy demand compared to pervaporation.For product purities of 99wt% of BuOH a hybrid pervaporation and distillation process saves around 50% of the energy demand compared to state of the art distillation. A sensitivity analysis of the pervaporation step reveals, that for the hybrid pervaporation and distillation process compared to state of the art distillation the energy demand decreases already exceeding 5wt% BuOH in the permeate stream.

Influence of hydrocarbon species on the removal of thiophene from FCC gasoline by using a spiral wound pervaporation module

Pervaporation is an emerging technology in the field of thiophene removal from the Fluid Catalytic Cracker (FCC) gasoline. The performance of pervaporation process for thiophene removal depends on different types of hydrocarbon species present in the FCC gasoline due to their distinctive transport properties in the membrane, as well as due to their distinct physical and thermal properties. In membrane modules, the presence of different hydrocarbon species may also affect the variations in flow variables such as the temperature and concentrations in the feed and permeate channels. This in turn may further influence the performance of the module. The present study shows how different hydrocarbon species present in the gasoline influence the performance of a spiral wound module. First, the experimental data for a number of binary mixtures are obtained for a variety of hydrocarbons and thiophene. This data is then analysed by using a mathematical model for the spiral wound module. The membrane transport parameters are determined by using a parameter estimation technique. The results indicate that the thiophene (C4H4S) removal from different binary mixtures may be sorted out based on the type of hydrocarbon species present in the binary mixtures as linear alkane>alkene>branched alkane>aromatic compounds. Results for a ternary mixture show that the same mathematical model may also be used for predictions of the module performance by assuming the ternary mixture to be equivalent to a binary mixture of two species: first is thiophene, and second species is a pseudo-species, having the average physical properties of two other hydrocarbons present in the ternary mixture. The same approach may be extended to a multicomponent feed of a real FCC gasoline, containing a variety of hydrocarbons and sulphur containing compounds. This approach may provide sufficiently accurate predictions with much lesser efforts in comparison to more rigorous, and much more tedious, multicomponent modelling.

Removal of 2-propanol from water by pervaporation using poly(vinylidene fluoride) membrane filled with carbon black

In the present study, several filled poly(vinylidene fluoride) (PVDF) membranes by the addition of various weight fractions from carbon black (CB) to the casting solution were prepared for the removal of 2-propanol from aqueous solution in pervaporation process. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), contact angle and swelling degree measurements were used to study morphology and properties of the prepared membranes. Separation experiments were carried out at a feed temperature of 45°C and a permeate pressure of 18mmHg. The results demonstrated that the addition of carbon black filler resulted in formation of the membranes with denser structure; lower permeation flux and degree of swelling; and higher crystallinity, separation factor, contact angle, and pervaporation separation index.

Membranes with Favorable Chemical Materials for Pervaporation Process: A Review

Among many purification processes, pervaporation is one of the promising technologies which is an indispensable component for chemical separations with low energy consumption, minimum contamination and ability to break up azeotropic mixtures. The key success of pervaporation process is dependent on the membrane features (chemical components and morphology). Application of membranes surveyed in three categories included organic solvent dehydration, removal of organics from solvent and separation of organic solvents. This article review discusses different types of pervaporation membranes from the perspective of membrane fabrication and materials in biofuel products.

Fabrication of nanohybrid polyetherimide/graphene oxide membranes: biofuel dehydration by pervaporation process

Nanohybrid (GO-PEI) membranes with hydrophilic property were synthesized and can be used to dehydrate biofuels such as n-butanol with high permeation and separation factor.

Preparation of PDMS/PVDF Composite Pervaporation Membrane Modified with Hydrophobic TiO2 Nanoparticles for Separating Formaldehyde Solution

In this paper, polydimethylsiloxane (PDMS) was blended with hydrophobic TiO2 nanoparticles and then coated on top of the polyvinylidene fluoride (PVDF) ultrafiltration membrane to form the (PDMS/TiO2)/PVDF composite membrane. The structure, morphology and physical property of the composite membrane were characterized by FTIR, SEM, contact angle measurement, and dry-wet swelling degree test. The TiO2 was uniformly distributed in the PDMS matrix, and the composite membrane showed higher affinity to formaldehyde than water. The membrane was used to separate the 1000 ppm formaldehyde water solution through a pervaporation (PV) process. The results showed that the membrane could selectively permeate formaldehyde over water and the best separation performance could be achieved at 50°C with a separation factor of 11.25, and a total flux of 187.72 g·m-2·h-1, which were better than the pristine PDMS/PVDF membrane with separation factor of 10.66 and total flux of 115.52 g·m-2·h-1. Hence, adding TiO2 not only increased the membrane flux, but also increased the separation factor of the composite membrane. This study showed that pervaporation technology had the potential for treating formaldehyde wastewater.

Must concentration by new zeolite membrane (KonKerTM) technology

In this work in this work the must concentration by pervaporative dehydration through a new In In this work in this work the must concentration by pervaporative dehydration through a new of zeolite membrane was compared to the common treatments of chaptalization and must concentration by nanofiltration. Must and wine analysis were conducted to assess if the new pervaporative dehydration process by zeolite membrane effects the must and wine composition, in another way than the other tested authorized processes. In general, the must and wine composition was not changed by the new procedure compared to the usual technologies. Sensory evaluation proof that results. The panelists were not able to distinguish the respective test variants significantly from each other.

Nonequilibrium Dissolution-diffusion Model for PDMS Membrane Pervaporation of ABE Water Binary System

Previous models of equilibrium dissolution-diffusion, pore flow and virtual phase change cannot describe the mass transfer process of pervaporation precisely. The fact that dissolution process on the surface of the membrane does not reach equilibrium is seldom emphasized in the literature. The aim of the present work is to develop the nonequilibrium dissolution-diffusion model (nonequilibrium model) for membrane pervaporation process. In this research, the steps of dissolution and desorption were treated as the pseudo surface reaction processes on the surface based on the hypothesis of nonequilibrium dissolution at the interface of the feed liquid and membrane. The semi-experimental model was set based on steady state mass transfer, ignoring the concentration polarization and adsorption at the permeation side. Through linear fitting of the flux with different thickness of the membrane, the diffusion coefficients and adsorption kinetic rate constants of the model were achieved with equilibrium partition coefficient estimated by UNIFAC-ZM model. The calculated values of the model were well in consistent with experimental flux in the vacuum pervaporation of acetone, butanol and ethanol with polydimethylsiloxane membrane. The nonequilibrium model and its parameters will be further applied for prediction of separation performance and selection of operation conditions.

Computational fluid dynamic modeling of a pervaporation process for removal of styrene from petrochemical wastewater

In this study, a predictive model was developed to describe the process of separation of volatile organic compounds.